Kenoplumbomicrolite

Chemical formula: (Pb,Na,Ca,◻)₂Ta₂(O,OH)₇

Kenoplumbomicrolite is a rare mineral from the microlite group, an oxide of tantalum and lead, found as small, yellowish-brown crystals.

## Characteristics Kenoplumbomicrolite is a rare mineral belonging to the pyrochlore supergroup and the microlite group. Its chemical composition is dominated by lead and tantalum. It forms small, well-formed, octahedral crystals that rarely exceed 1-2 mm in size. It usually occurs as single crystals or small aggregates, grown on other minerals. ## Physical Properties This mineral is characterized by a hardness of 6 on the Mohs scale. It has a high density, approximately 7.31 g/cm³, which is typical for minerals containing tantalum and lead. The luster is most often vitreous to resinous. It is translucent. ## Colors and Varieties Kenoplumbomicrolite occurs in a characteristic yellowish-brown color. No distinct color or commercial varieties have been identified. ## History and Name The mineral's name refers to its chemical composition and structure. The prefix "keno-" indicates a vacancy (empty site) at one of the cationic positions, "plumbo-" refers to the dominance of lead (Latin: *plumbum*), and "microlite" to its belonging to the microlite group. It was formally described as a new mineral in 2011, and its discovery was made on Mount Ploskaya in Russia. ## Applications Due to its rarity and small crystal size, kenoplumbomicrolite has no industrial application. It is solely an object of interest for collectors specializing in rare minerals or minerals from the pyrochlore group.

Properties

Mohs hardness
6
Luster
Vitreous to resinous
Streak
White
Density
7.310
Transparency
Translucent
Crystal system
Isometric

Diagnostic features

## Identification Kenoplumbomicrolite is identified by its characteristic octahedral crystal form, yellowish-brown color, and high density. It occurs in a specific geological environment – in alkaline pegmatites. Final identification requires advanced analytical methods, such as chemical composition analysis (EDS/WDS) and X-ray diffraction (XRD). ## Distinguishing from similar minerals It can be confused with other minerals from the microlite group, such as microlite, pyrochlore, or uranomicrolite. Distinguishing them "by hand" is practically impossible and requires specialized laboratory tests to determine the dominant elements in the composition. ## Crystal forms Kenoplumbomicrolite crystals typically have the form of regular octahedra {111}. They occur as single, isolated crystals or in small aggregates.

Geological environment

## Genesis Kenoplumbomicrolite forms in the late stages of crystallization of alkaline pegmatites, rich in rare earth elements, tantalum, and niobium. It is a hydrothermal or metasomatic mineral, crystallizing in altered parts of these pegmatites. ## Mineral associations This mineral co-occurs with other rare minerals typical of alkaline pegmatites. At the type locality (Mount Ploskaya), it was found in association with quartz, albite, microcline, lepidolite, pollucite, tantaleschynite-(Y), and various minerals from the microlite group. ## Localities The most important and, so far, the only confirmed occurrence of kenoplumbomicrolite is its type locality – Mount Ploskaya in the Western Keivy massif, Murmansk Oblast, Russia.

Rarity

Very rare

For collectors

## Quality criteria The most valued specimens by collectors are those with sharp, well-formed, and undamaged crystals of a distinct yellowish-brown color. The contrast with the surrounding host rock (matrix) on which the crystals are embedded is also important. Due to their small size, the perfection of the crystal form is crucial. ## Popular localities The only source of collector specimens is the type locality in Russia (Mount Ploskaya). Specimens from this location are highly sought after by collectors specializing in mineral systematics and "micromounts."

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Due to the presence of lead, direct contact with dust should be avoided, and hands should be washed after handling the mineral. The use of water is not recommended without certainty about the stability of the specimen and the host rock. ## What to avoid Avoid contact with acids and other aggressive chemicals that can damage the crystal surface. The mineral is brittle, so it should be protected from impacts and falls. It should not be heated or subjected to ultrasound. ## Storage Kenoplumbomicrolite specimens, due to their small size and scientific value, are best stored in specialized "micromount" boxes, which protect them from mechanical damage and dust. They should be stored in stable conditions, away from moisture.

External references

Sources

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